Wolff Luffer Makes U.S. Debut on San Francisco Skyscraper Build

Company News: Wolffkran

August 25, 2015 - A new attraction is rising on the San Francisco skyline in the form of the 802-ft.-tall skyscraper 181 Fremont Street. But the construction site is already an attraction now, with a brand new Wolff 700 B luffing-jib crane drawing attention to itself since the beginning of the year. The Wolff 700 B was bought by the crane rental company Maxim Crane Works L.P., and rented to the general contractor, Level 10 Construction, specifically for this project.

The tower crane is the first of its kind in the United States and represents the launch of a new generation of high-performance, fully electric Wolff luffing-jib cranes on metropolitan high-rise construction projects in the U.S.

The project required a crane with very high lifting capacities covering a wide working radius, fast line speeds, and as space-saving as possible. In search of the right crane, Maxim Crane Works struck gold with the traditional German crane manufacturer Wolffkran. The Wolff 700 B luffing-jib tower crane, first manufactured in 2010 and since tried and tested on construction sites around the world, fulfilled all technical demands made by the contractor, Level 10 Construction. Following an intense collaboration between all three parties involved in the planning phase, the luffer finally set off on its journey from the production facility in Heilbronn, Germany to San Francisco late last year, where it has been in operation since mid-January.

The Wolff 700 B has a maximum lifting capacity of up to 110,230 lbs. in three-fall operation, and a maximum tip load capacity of 36,380lbs at a jib radius of 164 ft. The heaviest lift on the site is a mega support column weighing just over 100,000 lbs. set at a 46 ft. radius. But the crane also has to handle heavy loads further out due to the exoskeletal design of the high-rise using heavy steel support columns on all six corners of the building.

Despite its power, the luffer stands on a slender tower, with section dimensions of only 7’ 7”, allowing for transport on regular trailers without any special road permits required. Even with its lifting capacity and hoisting speed of up 623 ft./min., the Wolff 700 B requires less power than you would think. The fully electrically operated crane is equipped with a stepless frequency controlled drive, making it energy efficient. It has comparatively low noise emissions and is pollution-free.

Equipped with the latest crane controls as standard, the crane has an extensive range of efficiency and safety features, such as automatic adjustment of all drives, recognition of output reserves, horizontal level luffing, slack rope monitoring, and comprehensive self- tests to support the driver to name just a few. It also includes the Wolffkran-patented, semi-automatic re-reeving mechanism which significantly facilitates switching between the 1-, 2- and 3-fall operation.

For a crane of this size category, the Wolff 700 B has a compact design and offers maneuverability, another big plus point on the 21,528-sq.-ft. plot in the densely built SoMa district. Of particular mention is its short counter jib with only 25’3”. Originally developed for the installation of wind turbines, the 700 B is not fit with the short counter jib as standard, allowing for an even closer positioning of the crane to the building.

But the crane is also space saving during the assembly. Thanks to Wolffkran’s patented design of the counter jib, individual component weights can be kept low and smaller mobile cranes used for the assembly. Further, the pre-assembly of crane components before their arrival on the site significantly reduces assembly time, which in turn keeps road closures to a minimum. The 700 B on the 181 Fremont construction site was completely assembled in just three days.

The luffer will be climbed externally alongside the building to a final tower height of 764 ft. Despite this height, the crane will only be tied to the building 10 times, thanks to the extremely sturdy, but comparatively slender 7’7” Wolff HT 23 tower sections.

Beyond its compact design and high load capacity the luffing crane offers practically all features required by the U.S. market, such as secondary brakes for the hoisting and luffing gears or the option of adding an auxiliary winch and hoist. The crane is compliant with the American ANSI standard for tower cranes and only minor modifications need to be made to the electrical system to adapt it to the American UL standards.

With Maxim Crane Works, Wolffkran has a strong partner at its side for the introduction of the Wolff 700 B into the U.S. market along with general contractor Level 10 Construction. In the end, the combination of state-of-the-art German engineering paired with expert crane services fulfilled the unique requirements at 181 Fremont. The Wolff 700 B in San Francisco marks the beginning of Wolffkran’s expansion in the U.S. market. This past spring, Wolffkran Inc., founded in the summer of 2014, officially opened its doors just outside Manhattan, to provide a comprehensive range of crane services, support, and supply of spare parts for customers in the New York area. There, a brand new Wolff 355 B, a smaller version of the 700 B, was erected at the WTC 3 site.